1. Field of The Invention
The present invention relates to a container for warming of infusion liquid and transfusion liquid and to an apparatus provided with such a container in order to warm physiological fluids.
2. Description of The Prior Art
Different embodiments of instruments and blood warmers are known. These embodiments are described in the essay "A Review of Blood Warmers for Massive Transfusion" by W. J. Russell, Anaesthesia and Intensive Care, Vol. II, No. 2, May 1974.
Essentially these embodiments can be divided into four groups.
1. Warming of the whole contents of a bag or of a bottle in a bucket of water of 37.degree. C. or in a microwave oven, warming the liquid to a suitable temperature by means of high frequency electromagnetic oscillation. The warming before infusion has drawbacks, namely that
it needs a relatively long time period to warm a bottle of blood; PA1 the liquid will be partly cooled down during infusion; PA1 an unmovable and much space-using apparatus has to be provided in the operating theatre when using a microwave oven; PA1 a monitoring of temperature of the warmed liquid is not possible; and PA1 a determination of the temperature by means of empirical data is difficult. PA1 a source of heating air to admit said container with heating air, PA1 a temperature measuring device with which the sections of the container are contactable to measure the temperature in said container, and PA1 a control device to control the source of heating air in response to the measured temperature.
2. Warming during infusion or transfusion wherein the liquid, for example blood, flows through a hose section conducted through water. This warming during infusion is commonly used. A hose up to 10 meters is somehow wound up, conducted through a bath of water and warms therefore the liquid up to the necessary 37.degree. C.
It is a drawback that the inevitably open bath of water warmed up to 37.degree. C. develops strong bacterial cultures and beside the sterility also the relative unmovableness, that is, the overflow of the water during hectic transport of the patient is a problem. Additionally it is not advantageous to handle wet and dripping instruments in the vicinity of the area of operation.
3. A hose to be wound around a warmed cylinder of aluminium or to be threaded in grooves. The drawbacks of this embodiment are a low effectiveness due to the commonly poor contact to hoses having a major thickness, a relatively long time period for warming due to said thickness, and a very long hose is necessary in order to avoid a thermodynamical shock in the patient by hypothermia.
4. A thin-walled bag having instruments connected thereto is disposed between a pair of heating plates for warming of the liquid flowing therethrough. This embodiment has the drawbacks that a bag with instruments is very expensive and that a high volume of liquid is necessary. This system will be very bulky due to the large surface necessary for an effective warming, as lack of space exists in the space for the nursing care of patients.